So after hearing prices for pre made units I'm thinking a couple hundred bucks and a trip to lowes will be well worth it... Anyone else done this? Or have any tips? Heres what Im currently thinking for design... 2 pieces of square tubing mounted to back bracket that surrounds muffler, attach 4 L shaped bars to the sqaure tubing. This is where 2 55 gal plastic trash cans will sit. Ill cut a retangular hole on the left side of left can and place chicken wire inside (ive heard this is essential for correct airflow). Cut a circular hole in each can between the 2 and connect with short 6" drain pipe. Use a register box that comes directly out at an angle towards back of mower and run pipe between that and the cans.